New Information Learnt

• What is the atomic radius?

  The size of an atom.
• What are the trends of an atomic radius?

  It increases down a group

  It decreases across a period
• What is electron shielding?

  the blocking of valence shell electron attraction by the nucleus, due to the presence of inner-electrons
• What is the ionic radius?

  An atoms atomic radius is different to the ionic radius. Atoms tend to lose or gain electrons in order to fill the outer shell therefore their radius changes.
• What changes to a cations radius?

  It is smaller than it's neutral atom as it loses its space-occupying electrons.
• What changes in an anions ionic radius?

  Anions are larger than their neutral atom because they have gained electrons.
• What is ionisation energy?

  The energy required to remove an electron from an atom or ion. It decreases down a group due to electron shielding. It increases across a period due to increased electrostatic attraction.
• What is Electronegativity?

  The ability of an atom to attract electrons in a chemical bond. It increases across a period due to the increase in nuclear charge.
• What is electron configuration?

  The arrangement of electrons in an atom or molecule.
• What is the Aufbau principle?

  Electrons fill orbitals of the lowest energy first.
• What is Pauli's Exclusion principle?

  Orbitals can hold a maximum of two electrons (of opposite spins).
• What is Hund's Rule?

  Electrons fill orbitals of the same energy level one at a time before pairing up.
• What are the two elements that are exceptions to the electronic configuration rules?

  Chromium and Copper.
• Define Relative Atomic Mass.

  The mass of an atom once the mass and percentage abundance of all isotopes have been considered, relative to carbon-12 isotope.
• What unit is used for atomic mass?

  AMU (atomic mass unit)
• Define Pure Substances.

  Are not mixed with any other type of substances. They have distinct measurable properties.
• What are the types of mixtures?

  Homogeneous and heterogeneous.
• What is homogeneous mixture?

  A mixture that has a uniform composition.
• What is a heterogeneous mixture?

  A mixture that has an inconsistent composition.
• What is spectroscopy?

  The use of light to determine information about substances.
• What is ground state?

  The most stable form of the atom.
• When an atom absorbs energy?

  Electrons can move from the ground state to a higher energy shell.
• An electron is not stable in the excited state and it emits light as it returns back to the ground state.
• What is the Lyman series?

  Transitions of electrons between the shells of (n>= to 2) and ground state shells. These transitions emit light in the UV region of the electromagnetic spectrum.
• What is Balmer Series?

  The transition of electrons between the (n>=3) and (n=2) shell. These transitions emit light in the visible region of the spectrum (400-750nm) They are seen as coloured lines in emission spectra.
• What is the Paschen Series?

  The transition of electrons between the (n>=4) and n=3 shells. These transitions emit light in the infrared region of the electromagnetic spectrum.
• What is a qualitive test?

  A test that identifies the characteristics of the element, for example the flame test.
• What is a quantative test?

  To determine the amount of an element for example the AAS.
• What is mass spectrometry?

  An analytical technique that is useful in determining the isotopic composition of an element. The samples are ionised and the ions formed are sorted according to their mass to charge ratio.
• What is the octet rule?

  Atoms can gain or lose electrons to achieve eight electrons in their valence shells. In doing this, they acquire a stable and low-eneergy noble gas electron configuration.
• What is a polyatomic ion?

  Consists of more than one type of atom.
• What is a mole?

  The quantity of a substance containing the same number of particles as there are atoms in exactly 12.000g of carbon-12 which is the same as Avogardo's number.
• What is a molar mass?

  The mass of one mole of a substance.
• What is relative atomic mass?

  The mass of an atom once the mass and percentage abundance of all isotopes have been considered, relative to the carbon-12 isotope.
• What is it called when an electron has moved to a higher energy level?

  Excited State as they have more energy than when in ground state.
• What is the energy change in reactions?

  In a chemical reaction, he bonds of reactants are broken, and the atoms rearrange to form new bonds of the products.
• What is an exothermic reaction?

  The products have less chemical energy than the reactants, the excess energy is released into the environment.
• What is an endothermic reaction?

  The products have more stored energy than the reactants, the extra energy is absorbed into the environment.
• What is electronegativity?


  Electronegativity is the measure of an atom's ability to attract electrons in a chemical bond.